Compact discs have become a standard medium for recording of audio and video information in digital format. The replication of compact discs involves molding of a raw disc, sputtering a metallic coating on the raw disc to form a metallized disc and applying a lacquer coating to the metallized disc. The raw disc is molded plastic having data pits which contain digital information. The metallic coating forms a reflective layer that allows a scanning laser beam to read the digital information from the compact disc (CD). The lacquer coating functions as a protective layer for the metallic coating and provides a smooth surface for printing.
The metallic coating on compact discs may be deposited on the substrate in a sputtering system. The compact discs are loaded into a sputtering chamber. The pressure in the chamber is reduced from atmospheric pressure to a pressure on the order of 1.3.times.10.sup.-3 -1.3.times.10.sup.-2 mbar (1-10 mTorr) for processing. The loading, processing and unloading of the compact discs is preferably automated. Compact discs must be handled in a way that avoids damage. During processing, the compact disc may be locked to a holder without covering any of the active surface to which the metallic coating is applied. The locking mechanism must be able to operate in vacuum without generation of contaminants or particles. The locking mechanism should be simple in construction and low in cost.
U.S. Pat. No. 5,195,794 issued Mar. 23, 1993 to Hummel, Jr. et al discloses a compact disc lifting system in which a plunger moves perpendicular to the central opening in a compact disc. Fins are positioned in slots in a housing and include legs and arms meeting at acute angles inside a formed seat. When the plunger moves to its extended position, fins rotate the legs outwardly, thereby engaging the lower edge of the center opening of the compact disc. The disclosed device is designed for manual handling of compact discs and is not practical for use in a vacuum processing chamber.